GB462264A - Improvements in or relating to controllers for electric circuits - Google Patents

Abstract

462,264. Electromagnetic switches. IGRANIC ELECTRIC CO., Ltd. April 7, 1936, No. 10249. Convention date, May 2, 1935. [Class 38 (v)] [Also in Group XXXV] An electric circuit control system, which may be employed in conjunction with electric welders, has means to effect the energization of the controlled circuit and a power-operated device rendered operative each time the controlled circuit is energized to effect de-energization thereof subject to a delay, said device having an operating winding and a restraining winding and said delay being caused by the electrical inertia inherent in the circuit of one of said windings. As shown in Fig. 1 applied to an electric welding plant depression of a push-button 7 energizes a main contactor 6 through contacts 10, 11 of a time lag relay 8. The main contacts of the contactor 6 complete the circuit to the primary winding 4 of a welding transformer 3, and the auxiliary contacts 6<a> complete a maintaining circuit for the contactor, this maintaining circuit including the contacts 10, 11 of the relay 8. The latter comprises a pivoted armature 9 subjected to the opposing forces of an operating coil 12 and a restraining coil 13. The coil 13 is normally connected across the supply lines L<1>, L<2> in series with a rectifier bridge 16 .. 19, the current through this coil passing through coils 6 and 12 in parallel but being insufficient to attract their controlled armatures. On depression of push-button 7 and closing of contactor 6, however, the coil 13 and rectifier bridge are shortcircuited both by the push-button and the contacts 6<a> so that the coil is de-energized and by virtue of its inductance commences to discharge through the resistance 22 and the rectifier bridge. Thus after a predetermined time delay the energization of the coil 13 falls to such a value that the energized operating coil 12 overcomes it and attracts the armature 9 breaking the maintaining circuit of the contactor 6 at contacts 10, 11. In modified arrangements the time-delay of operation may be modified by the value of the welding current by the addition of a coil in the time-lag relay which is either directly in or inductively coupled to, the welding transformer circuit.